2004ApJ...612.1147K

By analogy with the minimum-mass solar nebula, we construct a surface-density profile using the orbits of the 26 precise-Doppler planets found in multiple-planet systems: Σ=2200(a/1AU)^–βg/cm2, where a is the circumstellar radius and β=2.0±0.5. The minimum-mass solar nebula (β=1.5) is consistent with this model, but the uniform-α accretion disk model (β~1) is not. In a nebula with β>2, the center of the disk is the likely cradle of planet formation.